<?php
class Lib_Ip{
    public static function get_ip(){

        $realip = '0.0.0.0';

        if (isset($_SERVER)){
            if (isset($_SERVER['HTTP_X_FORWARDED_FOR'])){
                $arr = explode(',', $_SERVER['HTTP_X_FORWARDED_FOR']);
                /* 取X-Forwarded-For中第一个非unknown的有效IP字符串 */
                foreach ($arr AS $ip){
                    $ip = trim($ip);

                    if ($ip != 'unknown'){
                        $realip = $ip;

                        break;
                    }
                }
            }
            elseif (isset($_SERVER['HTTP_CLIENT_IP'])){
                $realip = $_SERVER['HTTP_CLIENT_IP'];
            }
            else{
                if (isset($_SERVER['REMOTE_ADDR'])){
                    $realip = $_SERVER['REMOTE_ADDR'];
                }
                else{
                    $realip = '0.0.0.0';
                }
            }
        }
        else{
            if (getenv('HTTP_X_FORWARDED_FOR')){
                $realip = getenv('HTTP_X_FORWARDED_FOR');
            }
            elseif (getenv('HTTP_CLIENT_IP')){
                $realip = getenv('HTTP_CLIENT_IP');
            }
            else{
                $realip = getenv('REMOTE_ADDR');
            }
        }

        preg_match("/[\d\.]{7,15}/", $realip, $onlineip);
        $realip = !empty($onlineip[0]) ? $onlineip[0] : '0.0.0.0';

        return $realip;
    }
}